Louis-Alexandre Berthier (20 November 1753 1 June 1815), Prince of Neuchtel and Valangin, Prince of Wagram, was a French Marshal of the Empire who served during the French Revolutionary Wars and the Napoleonic Wars. He was twice Minister of War of France and served as chief of staff to Napoleon Bonaparte.

Born into a military family, Berthier served in the French Army and survived suspicion of monarchism during the Reign of Terror before a rapid rise in the ranks of the French Revolutionary Army. Although a key supporter of the coup against the Directory that gave Napoleon supreme power, and present for his greatest victories, Berthier strongly opposed the progressive stretching of lines of communication during the Russian campaign. Allowed to retire by the restored Bourbon regime, he died of unnatural causes shortly before the Battle of Waterloo. Berthier's reputation as a superb operational organiser remains strong among current historians.

The Roman Republic (Italian: Repubblica Romana) was a sister republic of the First French Republic. It was proclaimed on 15 February 1798 after Louis-Alexandre Berthier, a general of Napoleon, had occupied the city of Rome on 10 February. It was led by a Directory of five men and comprised territory conquered from the Papal States. Pope Pius VI was exiled to France and died there in August 1799. The republic immediately took control of the other two former-papal revolutionary administrations, the Tiberina Republic and the Anconine Republic. The Roman Republic proved short-lived, as Neapolitan troops restored the Papal States in October 1799.